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      01-27-2020, 09:23 AM   #1
Muntter
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Issue with LC on UK car

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I ran a launch control on Sat morning and all was as it should be.
A 10 mile drive later, I tried another. While it all seemed ok, the revs were around 3k and within a couple of seconds, they drop to around 2300. Then I lift the break and the car launched forward. Until that is it hit the red line in 1st, and just bounced off it several times.
Thinking I must have made some error in the set up sequence (difficult as my M1 button basically applied everything to do an LC), I tried a few more times, same result, wouldn’t change gear and stuck in 1st.

I haven’t tried since, but I’m aware that getting it wrong and bouncing off the red line is not ideal for the car, yet how else can I test LC without doing as LC?

My thought was, if I wasn’t in LC mode, surely the revs would hit the red line before I even launched? The fact they are 3k and drop to around 2500 with my foot fully down, implies I’m in LC mode, right?

I have idrive 7 fwiw

Last edited by Muntter; 01-27-2020 at 01:23 PM..
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      01-27-2020, 02:19 PM   #2
Simon H
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Did you see the flag on the good launch ?, and did you see the flag on the failed launches ?. If you dont see the flag straight away, you are not in launch mode, and i would abort it straight away.
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      01-27-2020, 05:27 PM   #3
Muntter
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Quote:
Originally Posted by Simon H View Post
Did you see the flag on the good launch ?, and did you see the flag on the failed launches ?. If you dont see the flag straight away, you are not in launch mode, and i would abort it straight away.
I don’t believe we get a flag, or any other kind of identifier with idrive 7........
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      01-28-2020, 01:26 AM   #4
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Quote:
Originally Posted by Muntter View Post
I don’t believe we get a flag, or any other kind of identifier with idrive 7........

Is that correct ?, surely there should be a flag or some sort of ID ?
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      01-28-2020, 05:44 AM   #5
DannyA
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You should still get the flag - are you looking in the middle of the dash?
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      01-28-2020, 08:48 AM   #6
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Originally Posted by DannyA View Post
You should still get the flag - are you looking in the middle of the dash?
I’ll have a look this afternoon. By middle of the dash, do you mean the instrument display?
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      01-28-2020, 09:49 AM   #7
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Yes sorry - between rev counter and speed
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      01-28-2020, 10:25 AM   #8
Simon H
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Just reading your post again, im almost sure you have not been in launch mode. If you are bouncing off the limiter in first, with your foot still planted, tells me you were not in launch mode, along with no flag ?. Did it feel like the car was dragging and fighting when held on the brakes at the very beginning ?. For some unknown reason, launch is not there every time ive tried, not on my current car, but other M5s ive tried, it seems to be a little fickle, but as soon as the flag pops up, you are good to go. I cant see BMW not having this flag anymore ?. Let us know.
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      01-28-2020, 04:31 PM   #9
Muntter
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Quote:
Originally Posted by Simon H View Post
Just reading your post again, im almost sure you have not been in launch mode. If you are bouncing off the limiter in first, with your foot still planted, tells me you were not in launch mode, along with no flag ?. Did it feel like the car was dragging and fighting when held on the brakes at the very beginning ?. For some unknown reason, launch is not there every time ive tried, not on my current car, but other M5s ive tried, it seems to be a little fickle, but as soon as the flag pops up, you are good to go. I cant see BMW not having this flag anymore ?. Let us know.
Still not observed the flag, was raining today
However, I think when it went wrong it may have been this.....I read different things everywhere and one thing I read was the longer you hold the accelerator pedal before lifting the brake, the more boost the turbos build. When I try to hold for a couple of seconds the revs drop and the car revs to the red line and bounces. I believe the story of building turbo pressure is somewhat untrue and anything over a second or so seems to pop you out of LC?
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      01-28-2020, 04:54 PM   #10
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Yeah the longer you hold the accelerator it does build more boost. Are you definitely following the launch control steps? Also is the car warm - you need to do some driving before it will let you launch
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      01-29-2020, 02:16 AM   #11
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Quote:
Originally Posted by DannyA View Post
Yeah the longer you hold the accelerator it does build more boost. Are you definitely following the launch control steps? Also is the car warm - you need to do some driving before it will let you launch
Is this from your own experience? I ask because I’ve also read that you have to lift the break very quickly or it drops out of LC mode and this seems to be my experience.
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      01-29-2020, 03:38 AM   #12
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If you like I can do a video today? I don't launch often but last time I did it was pretty simple, I just waited for the flag and let off the brake, didn't have to do anything at breakneck pace etc.

What steps are you doing to try and get it to launch?
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      01-29-2020, 05:17 AM   #13
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Quote:
Originally Posted by DannyA View Post
If you like I can do a video today? I don't launch often but last time I did it was pretty simple, I just waited for the flag and let off the brake, didn't have to do anything at breakneck pace etc.

What steps are you doing to try and get it to launch?
Yes plz Dan, that would help a lot.
I’ve set my M1 button to set the right settings, then I just hold the brake and floor the loud pedal, then lift off the brake. I’ve only done 5 launches, taking around 9 attempts (4 fails) so If I see it from your vid, it will show me if I’m doing wrong, or it’s a return to dealer
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      01-29-2020, 06:51 AM   #14
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Just went out to check and assuming I am not doing something stupid, I can confirm that idrive v7 (live cockpit) does not have a LC flag, writing or any other way of telling you that your in LC mode.

Not very good eh!
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      01-29-2020, 06:55 AM   #15
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Mental! So how do you know it's going to launch
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      01-29-2020, 08:37 AM   #16
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Quote:
Originally Posted by Muntter View Post
Just went out to check and assuming I am not doing something stupid, I can confirm that idrive v7 (live cockpit) does not have a LC flag, writing or any other way of telling you that your in LC mode.

Not very good eh!

I think you are incorrect about the flag. I know its not an M5, but look at this M850i doing launch, with the same dash software ?, around the 7 second into the video mark, then later on too.



Last edited by Simon H; 01-29-2020 at 09:31 AM..
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      01-29-2020, 10:02 AM   #17
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Hey,

Let me know if this helps:

Code:
https://vimeo.com/387997980
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      01-29-2020, 05:57 PM   #18
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Quote:
Originally Posted by Muntter View Post
Just went out to check and assuming I am not doing something stupid, I can confirm that idrive v7 (live cockpit) does not have a LC flag, writing or any other way of telling you that your in LC mode.

Not very good eh!
I can confirm iDrive 7 on an M5 does show the launch control flag.
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